Table 11- 4 Response To A Recurring Comparison Error; Table 11- 5 Reaction To Checksum Errors - Siemens SIMATIC S7-400H System Manual

System and operating states of the S7–400H
11.4 Self-test
RAM/POI comparison error
If the self-test returns a RAM/POI comparison error, the fault-tolerant system quits redundant
mode and the standby CPU enters ERROR-SEARCH mode (in default configuration). The
cause of the error is written to the diagnostic buffer.
The response to a recurring RAM/POI comparison error depends on whether the error
occurs in the subsequent self-test cycle after troubleshooting or not until later.
Table 11- 4
Comparison error recurs ...
in the first self-test cycle after troubleshooting
after two or more self-test cycles after
troubleshooting
Checksum errors
When a checksum error occurs for the first time after the last POWER ON without backup,
the system reacts as follows:
Table 11- 5
Time of detection
During the startup test after
POWER ON
In the cyclic self-test
(STOP or standalone mode)
In the cyclic self-test
(redundant system mode)
In the
ERROR-SEARCH mode
Single-bit errors
The cause of the error is written to the diagnostic buffer.
In an F system, the F program is informed that the self-test has detected an error the first
time a checksum error occurs in STOP or standalone mode. The reaction of the F program
to this is described in the
138
Response to a recurring comparison error
Reaction to checksum errors
System response
The faulty CPU enters the DEFECTIVE state.
The fault-tolerant system switches to standalone mode.
The error is corrected. The CPU remains in STOP or in standalone
mode.
The error is corrected. The faulty CPU enters ERROR-SEARCH
mode.
The fault-tolerant system switches to standalone mode.
The faulty CPU enters the DEFECTIVE state.
The CPU calls OB 84 after detection and elimination of the error.
S7-400F and S7-400FH Automation Systems
Reaction
The standby CPU first enters ERROR-SEARCH
mode, and then goes into STOP.
The fault-tolerant system switches to standalone
mode.
Standby CPU enters ERROR-SEARCH mode.
The fault-tolerant system switches to standalone
mode.
System Manual, 03/2012, A5E00267695-11
manual.
S7-400H